The objective of this study was to evaluate economic and health effects of sumatriptan relative to customary therapy in Canada. The relationship between treatment and functionality was established based on analysis of existing data from a multinational study. A Monte Carlo model was developed to simulate 1 year for each of customary therapy and six sumatriptan formulations. Costs are expressed in 1998 Canadian dollars. Sumatriptan is expected to reduce the time spent with migraine symptoms and resulting time lost. Under customary therapy, the annual cost of lost time is estimated at £908 ($1973). With sumatriptan, these costs ranged from £406 ($882) with subcutaneous sumatriptan to £577 ($1254) with nasal sumatriptan 10 mg, saving £331–502 ($719–1091) in the annual cost of time lost. All these benefits are expected to be obtained at an additional drug cost ranging from £869 ($1889) for subcutaneous sumatriptan to £278 ($605) for sumatriptan suppository. The cost of sumatriptan treatment is significantly offset by a substantial reduction of costs associated with time lost due to migraine symptoms.